Field of the Invention
The present invention relates to a structure in which a resolver is attached to a flange.
Description of Related Art
For example, a resolver is used for detecting a rotation angle of a rotating part in an apparatus. At this time, a stator of the resolver is fixed to a housing of the apparatus, etc. Generally, a standard resolver is prepared; however, there are various types of apparatus for fixing the resolver. Thus, the resolver is mounted to the apparatus by fixing the resolver to the flange and fixing the flange to the apparatus. As a structure for fixing the resolver to the apparatus, etc., for example, techniques described in Japanese Unexamined Patent Application Laid-open No. 2006-94582 and Japanese Unexamined Patent Application Laid-open No. 2003-23761 are known.
In the case in which the resolver is fixed to the flange by press-fitting, measuring accuracy of the resolver is often decreased by fixing to the flange. In the following, this point will be explained.
For example, a VR (valuable reluctance) type resolver has a ring-shaped stator and a rotor arranged on the inside of the stator. Here, the stator has multiple salient poles that protrude inwardly to the axial center and are arranged along a circumferential direction, and an exciting coil, a sine phase detecting coil and a cosine phase detecting coil are wound around these salient poles. The rotor is made of magnetic material, and poles that protrude in a radial direction are provided. When the rotor rotates, a distance between each coil and the rotor surface periodically changes, a length of magnetic path between the cosine phase detecting coil and a length of magnetic path between the exciting coil and the sine phase detecting coil change due to the distance change, a sine phase output waveform from the sine phase detecting coil and a cosine phase output waveform from the cosine phase detecting coil change due to the lengths, and these waveform changes are detected. Then, change of a rotation angle of the rotor is calculated from the sine phase output waveform and the cosine phase output waveform.
In addition, in a structure in which the resolver is simply fixed to the flange by press-fitting, strong stress is applied to the stator in an axial center direction with the press-fitting, and a deformation is generated in the stator. A magnetic path is formed on the inside of the stator; however, when the deformation is generated, it affects a magnetic path length or a magnetic resistance in the stator. Due to this effect, angle detecting accuracy of the resolver is deteriorated
According to the above reason, there is a problem in that the angle detecting accuracy is decreased when attaching to an apparatus, even if quality as a product of the resolver itself is ensured. In view of such circumstances, it is an object of the present invention to provide a resolver having a structure in which a resolver is attached to a flange by press-fitting and in which strong stress that affects an angle detecting accuracy of a stator of the resolver is not applied.